package com.hmdp.service.impl;

import com.hmdp.service.ILock;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;

import java.util.Collections;
import java.util.UUID;
import java.util.concurrent.TimeUnit;

public class SimpleRedisLock implements ILock {

    private StringRedisTemplate stringRedisTemplate;
    //锁名称（业务名）
    private String name;
    //锁前缀
    private static final String KEY_PREFIX = "locks:";

    private static final String ID_PREFIX = UUID.randomUUID().toString() + "-";

    public SimpleRedisLock(StringRedisTemplate stringRedisTemplate, String name) {
        this.stringRedisTemplate = stringRedisTemplate;
        this.name = name;
    }

    @Override
    public boolean tryLock(long timeoutSec) {
        // 获取线程标识
        long threadId = Thread.currentThread().getId();

        // 获取锁
        Boolean success = stringRedisTemplate.opsForValue().setIfAbsent(KEY_PREFIX + name, ID_PREFIX+threadId, timeoutSec, TimeUnit.SECONDS);
        //自动拆箱会有空指针风险
        return Boolean.TRUE.equals(success);
    }


    private static final DefaultRedisScript<Long> UNLOCK_SCRIPT;
    static {
        UNLOCK_SCRIPT = new DefaultRedisScript<>();
        UNLOCK_SCRIPT.setLocation(new ClassPathResource("unlock.lua"));
        UNLOCK_SCRIPT.setResultType(Long.class);
    }

    @Override
    public void unLock() {

        String threadId  = ID_PREFIX+Thread.currentThread().getId();

//        String id =  stringRedisTemplate.opsForValue().get(KEY_PREFIX+name);

        stringRedisTemplate.execute(
                UNLOCK_SCRIPT,
                Collections.singletonList(KEY_PREFIX + name),
                threadId);
        //释放锁之前加一个判断
//        if (threadId.equals(id)){
//            //释放锁
//            stringRedisTemplate.delete(KEY_PREFIX + name);
//        }


    }
}
